1. Field of the Invention
The present invention relates generally to pressure sensors used in a fluid conduit to sense an increase in a predetermined flow rate or is used with a rupture disk or other fluid flow control device (such as a valve) and specifically relates to a metallic pressure sensor comprised of at least one petal for use in low and high temperature applications and that causes a discontinuity (open circuit) in an electrical circuit as a result of predetermined pressure differential across the sensor.
2. General Background
Rupture disk are commonly used in piping systems and on pressure vessels to quickly relieve pressure within the vessel or system in order to prevent damage to the vessel or to equipment associated with the vessel.
Typically, rupture disks are positioned in a piping system between standard pipe fittings such as flanges or are operatively coupled to a closed fluid container in which pressure can build. When a rupture disk breaks as a result of excess fluid pressure, an indication that such breaking has occurred is desirable in many situations.
Sensors have been patented that are directed to the concept of monitoring a rupture disk and indicating when that rupture disk has broken. Examples of such systems can be found in U.S. Pat. No. 3,770,918 issued Nov. 6, 1979; U.S. Pat. No. 4,342,988 issued Aug. 3, 1982; U.S. Pat. No. 4,408,194 issued Oct. 4, 1983; and U.S. Pat. No. 4,978,947 issued Dec. 18, 1990. Further, Sensors are commonly used to indicate when there is fluid flow or pressure buildup. For example, pressures increase in a storage tank.
The '947 patent discloses a sensor and a rupture disk assembly. The sensor is comprised of a rupturable member adapted to be clamped across a fluid flow passageway and having at least one opening formed therein for weakening a portion of the sensor. An electric current conductor adapted to be electrically connected in an alarm circuit is positioned across the weakened portion of the sensor rupturable member whereby, when the member ruptures as a result of fluid pressure exerted thereon, the conductor also ruptures to cause an alarm.
The Fritz U.S. Pat. No. 4,951,697 entitled "Rupture Disk Failure Indicating Apparatus" provides apparatus for visually indicating the failure of a rupture disk comprised of an elongated hollow body member, a piston disposed in the body member which is moved therein by pressurized fluid pressure exerted thereon, and an elongated indicator pin which is pushed by the piston through an opening in the body when pressurized fluid causes the piston to move therein. The body member includes a pressurized fluid exhaust port which is opened by the movement of the piston. Pressurized fluid exhausted through the exhaust port can be vented to prevent abnormal rupture disk operation or it can be utilized to activate an alarm.